Railway brakes

ABSTRACT

A railway vehicle brake arrangement comprises a disc brake and a tread brake, both associated with one and the same wheel and axle set, and a power actuator. Tee disc brake has a pair of caliper levers carrying respective brake shoes, and the actuator is operative to actuate the caliper levers to apply the brakes shoes. The actuator is mechanically coupled indirectly to one of the caliper levers through an equalizing lever which forms part of the transmission to the tread brake.

United States Patent [1 1 [111 3,791,491 Tickle Feb. 12, 1974 RAILWAYBRAKES 2,359,788 10/1944 Pierce 188/33 2 [75] Inventor: Colin JohnFrederick Tickle, E33; i 2 3 Ty e ey Eng and I l y 7 Asslgnee dLlmlted"mmgham Primary Examiner-Duane A. Reger Attorney, Agent, or Firm-SamuelScrivener, Jr. et al. [22] Filed: July 14, 1972 [2!] Appl. No.: 271,663

- [57] ABSTRACT [30] Foreign Applicafimi priority Data A railway vehiclebrake arrangement comprises a disc July 16, 197] Great Britain 33,51l/7l brake and a tread brake both associated with one and the same wheeland axle set, and a power actuator. [52] US. Cl 188/70 R, 188/33, 188/59Tee disc brake has a pair of caliper levers carrying [51] Till. Cl B611]11/14 spective brake Shoes, and the actuator is operative to [58] Fleldof Search 188/33 70 70 actuate the caliper levers to apply the brakesshoes. 188/74 107 The actuator is mechanically coupled indirectly to oneof the caliper levers through an equalizing lever which [56] ReferencesCited forms part of the transmission to the tread brake.

UNITED STATES PATENTS 420,815 2/1390 Martin 188/70 R 7 Claims, 3 DrawingFigures RAILWAY BRAKES This invention relates to railway vehicle brakes,and is particularly, but not exclusively, applicable to brakes for motorbogies of railway vehicles.

In such a bogie, an electric motor or gear case is mounted co-axiallywith the axle, with the result that there is usually insufficient spaceinboard of the wheel to mount a brake disc on the axle, but if thebrakes act only to the wheel tread, the latter tends to overheat locallydue to the concentration of braking effort on a relatively small area ofthe surface of the wheel. It is known to provide a brake arrangement inwhich the heat input per unit of braking surface area of the wheel isreduced, by providing both a disc-brake and a tread brake on the samewheel, and the present invention provides a new and improved brakearrangement of this general character.

In accordance with the invention there is provided a railway vehiclebrake arrangement comprising a disc brake having a pair of caliperlevers carrying respective brake shoes, and a tread brake, bothassociated in use with one and the same wheel and axle set, and a singlepower actuator operative to actuate the caliper levers to apply the discbrake shoes, one of the caliper levers being mechanically coupledindirectly to the actuator through an equilizing lever which forms partof the transmission to the tread brake.

The braking effort is thus distributed between the two brakes.

Three embodiments of a railway brake arrangement in accordance with theinvention will now be described, by way of example, with reference tothe accompanying drawings wherein: p FIG. 1 is a diagrammatic view ofone embodiment of the invention;

FIG. 2 is a diagrammatic view of a second embodiment of the invention;and FIG. 3 is a diagrammatic view of a third embodiment of theinvention.

In each embodiment, the arrangement comprises a disc brake having a pairof caliper levers 1a, 1b arranged one on either side of a wheel 2 andcarrying at their outer ends respective brake shoes 3, a yoke 4pivotally connecting the two levers la, 1b; a tread brake having a brakeblock 5 connected to astrut 6 and slidable in fixed guides orsuspendedon swinging links 7 from a fixed support and a power actuator 8 foractuating both the disc and tread brakes. The power actuator housing 9is pivotally connected to one of the caliper levers lb and the piston ordiaphragm rod 10 of the actuator is pivotally connected to the inner endof an equalizing lever 11 which is pivotally mounted at its centre 12 onthe caliper lever la. The outer end of the equalizing lever 1 l ispivotally connected to one arm of a bell crank lever 13 by a link 14,the other arm of the bell crank lever being pivotally connected to thestrut 6 of the tread brake. In the arrangements of FIGS. 1 and 3 thebell crank lever 13 is pivotally mounted at its angle on the yoke 4,whereas in the arrangement of FIG. 2 the lever 13 is mounted on a fixedframe member of the vehicle.

In operation pressure fluid is supplied to the actuator 8 and thediaphragm rod 10 moves to rotate the equalizing lever 11 about itspivotal connection 12 with the lever 1a and the movement is transmittedthrough the link 14, bell crank lever 13, and strut 6 to the tread brakeblocks 5 to apply the brake to the periphery of wheel 2. Reaction at thepivotal connection 12 acts to rotate the lever la to apply theassociated brake shoe 3 against a disc 15 secured to one side of thewheel, and the movement of the actuator housing 9 effects rotation ofthe lever 1b to apply the asociated brake shoe 3 against a disc 16secured to the other side of the wheel. It will be understood that thebrake shoes 3 could clamp a disc rotatable with the wheel 2, or thewheel web itself.

It will be appreciated that in the arrangement of FIG. 1 the yoke 4 isrigidly mounted on the frame of the sprung mass of the vehicle so thatwhen the brakes are applied the drag forces on the disc brake shoes 3are transferred through the caliper levera 1a,b and yoke 44 to thevehicle frame. Thus, no further support for the shoes 3 is required. Thetread brake reaction force is also transferred through the yoke to thevehicle frame. In the arrangement of FIG. 2, however, the tread brakelinks 7 are rigidly mounted on' the vehicle frame, the bell crank lever13 is carried by a support 16 rigidly fixed to the frame, and movementof the disc shoes 3 must be constrained, for example by drag links sus-3 pending the shoes 3 from the vehicle frame in known manner. In thearrangement of FIG. 3, the links 7 and power actuator 8 are rigidlymounted on the vehicle frame, and the shoes 3 must be constrained, forexample by links'as described above.

Many other variations and modifications will, of course, be possiblewithin the scope of the invention. For example, the illustrated poweractuator could be replaced by a duplex power actuator, the housing ofwhich may be fixed to the vehicle bogie. The equalizing lever 11 andcaliper lever lb would then be rotated by a pair of pistons ofdiaphragms, respectively when pressure fluid is supplied between them.In this arrangement the bellcrank lever 13 is pivotally mounted on thevehicle bogie and the brake shoes 3 are constrained by rigid links, aspreviously described. Further, the pivotal connection 12 may be offsetfrom the centre of the equalizing lever 11.

Normally the links of the caliper levers and equalizing lever are soproportional as to provide equal forces at the two shoes 3 and therequired porportion of the total braking force at the tread brake block.

In a further alternative arrangement the equalizing lever is connecteddirectly to the tread brake and by means of a link to one arm of thebell crank lever, the other arm of which is coupled to one of thecaliper levers.

The tread brake block 5 can be made as a clearing or friction-increasingmember which is operable to clear the periphery of the wheel or todeposit thereon friction-increasing material;to increase adhesionbetween the wheel and the rail upon which the wheel is running, in orderto reduce the risk of skidding.

I claim:

1. In or for a railway vehicle, a brake arrangement comprising a discbrake having a pair of caliper levers carrying respective brake shoes,and a tread brake, both associated in use with one and the same wheeland axle set of the vehicle; a single power actuator operative to acuatesaid caliper levers to apply said disc brake shoes and tread braketransmission means including equalizing means coupled to said actuator,means indirectly coupling one of said caliper levers to said actuatorthrough said equalizing means and means directly coupling said othercaliper lever to said actuator.

2. In or for a railway vehicle, a brake arrangement comprising a discbrake having a pair of caliper levers carrying respective brake shoes,and a tread brake, both associated in use with one and the same wheeland axle set of the vehicle; a single power actuator operative toactuate said caliper levers to apply said disc brake shoes, and treadbrake transmission means including equalizing means coupled to saidactuator; wherein said actuator is mechanically coupled indirectly toone of said caliper levers through said equalizing means, said treadbrake including a tread brake block, and said transmission meansincluding a bell crank lever connected between said thread brake blockand said equalizing means.

3. An arrangement according to claim 2, further comprising a yoke memberpivotally connected to said caliper levers, said bell crank lever beingpivotally mounted on said yoke member.

4. An arrangement according to claim 3 wherein said yoke member isrigidly mounted in use on a part of the vehicle structure.

5. An arrangement according to claim 2, wherein said bell crank lever ispivotally mounted in use on a part of the vehicle structure.

6. An arrangement according to claim 1 wherein said actuator is mountedin use on a part of the vehicle structure.

7. In or for a railway vehicle, a brake arrangement comprising a discbrake and a tread brake, both associated with one and the same wheel andaxle set of said vehicle, said wheel havingbraking surfaces on oppositesides thereof and at the periphery thereof, a power actuator; and treadbrake transmission means including an equalizing lever pivotallyconnected at its inner end to said power actuator and a bell crank leverone arm of which is connected to the outer end of said equalizing lever;wherein said disc brake comprises a pair of brake shoes for engagementwith said braking surfaces on opposite sides of said wheel, a pair ofcaliper levers which carry at their outer ends said brake shoes, one ofsaid caliper levers being mechanically coupled at its inner end directlyto said actuator and the other of said caliper levers being coupled atits inner end to said equalizing lever intermediateits ends, and a yokemember which is pivotally connected to said caliper levers intermediatetheir ends; and wherein said tread brake comprises a brake block forengaging said braking surface at the periphery of said wheel andmechanically coupled to the other arm of said bell crank lever, wherebyoperation of said power actuator causes simultaneous actuation of saiddisc and tread brakes.

1. In or for a railway vehicle, a brake arrangement comprising a discbrake having a pair of caliper levers carrying respective brake shoes,and a tread brake, both associated in use with one and the same wheeland axle set of the vehicle; a single power actuator operative to acuatesaid caliper levers to apply said disc brake shoes and tread braketransmission means including equalizing means coupled to said actuator,means indirectly coupling one of said caliper levers to said actuatorthrough said equalizing means and means directly coupling said othercaliper lever to said actuator.
 2. In or for a railway vehicle, a brakearrangement comprising a disc brake having a pair of caliper leverscarrying respective brake shoes, and a tread brake, both associated inuse wiTh one and the same wheel and axle set of the vehicle; a singlepower actuator operative to actuate said caliper levers to apply saiddisc brake shoes, and tread brake transmission means includingequalizing means coupled to said actuator; wherein said actuator ismechanically coupled indirectly to one of said caliper levers throughsaid equalizing means, said tread brake including a tread brake block,and said transmission means including a bell crank lever connectedbetween said thread brake block and said equalizing means.
 3. Anarrangement according to claim 2, further comprising a yoke memberpivotally connected to said caliper levers, said bell crank lever beingpivotally mounted on said yoke member.
 4. An arrangement according toclaim 3 wherein said yoke member is rigidly mounted in use on a part ofthe vehicle structure.
 5. An arrangement according to claim 2, whereinsaid bell crank lever is pivotally mounted in use on a part of thevehicle structure.
 6. An arrangement according to claim 1 wherein saidactuator is mounted in use on a part of the vehicle structure.
 7. In orfor a railway vehicle, a brake arrangement comprising a disc brake and atread brake, both associated with one and the same wheel and axle set ofsaid vehicle, said wheel having braking surfaces on opposite sidesthereof and at the periphery thereof, a power actuator; and tread braketransmission means including an equalizing lever pivotally connected atits inner end to said power actuator and a bell crank lever one arm ofwhich is connected to the outer end of said equalizing lever; whereinsaid disc brake comprises a pair of brake shoes for engagement with saidbraking surfaces on opposite sides of said wheel, a pair of caliperlevers which carry at their outer ends said brake shoes, one of saidcaliper levers being mechanically coupled at its inner end directly tosaid actuator and the other of said caliper levers being coupled at itsinner end to said equalizing lever intermediate its ends, and a yokemember which is pivotally connected to said caliper levers intermediatetheir ends; and wherein said tread brake comprises a brake block forengaging said braking surface at the periphery of said wheel andmechanically coupled to the other arm of said bell crank lever, wherebyoperation of said power actuator causes simultaneous actuation of saiddisc and tread brakes.